Evaluation of parietal pleural adhesion and invasion in subpleural lung cancer: value of B-mode ultrasound and contrast-enhanced ultrasound

Background:The parietal pleural adhesion/invasion of lung cancer can contribute substantially to poor prognosis and difficulty in surgery. The value of ultrasound in evaluating the parietal pleural adhesion or invasion (pleural adhesion/invasion) of lung cancer remains uncertain. This study investigated the value of B-mode ultrasound and contrast-enhanced ultrasound (CEUS) in diagnosing parietal pleural adhesion/invasion of subpleural lung cancer. Methods:The study animals included 40 male New Zealand white rabbits. A rabbit subpleural lung cancer model was constructed by injecting VX2 tumor tissue under ultrasound guidance. In the 1-3 weeks after subpleural lesion formation, parietal pleural adhesion/invasion of the largest subpleural lesion was evaluated with B-mode ultrasound and CEUS by two sonographers. The parietal pleural adhesion/invasion was also determined using the gold standard method of findings from anatomical and pathological examination. Results:Ultimately, 34 rabbits were subjected to complete ultrasonic evaluation. There were 20 and 14 cases with and without parietal pleural adhesion/invasion, respectively, as confirmed by anatomical and pathological evaluations. The diagnostic sensitivity, specificity, and accuracy of sonographer 1 using B-mode ultrasound were 50.0% [95% confidence interval (CI): 26.0-74.0%], 100%, and 70.6% (95% CI: 54.5-86.7%), respectively; for CEUS, they were 90.0% (95% CI: 75.6-100.0%), 100.0%, and 94.1% (95% CI: 85.8-100.0%), respectively. The diagnostic sensitivity, specificity, and accuracy of sonographer 2 using B-mode ultrasound were 45.0% (95% CI: 21.1-68.9%), 92.9% (95% CI: 77.5-100.0%), and 64.7% (95% CI: 47.8-81.6%), respectively; for CEUS, they were 85.0% (95% CI: 67.9-100.0%), 100.0%, and 91.2% (95% CI: 81.1-100.0%), respectively. The diagnostic accuracy of sonographer 1 was higher with CEUS than with B-mode ultrasound, but not significantly so (94.1% vs. 70.6%; P=0.08). The diagnostic accuracy of sonographer 2 was significantly higher with CEUS than with B-mode ultrasound (91.2% vs. 64.7%; P=0.03). The interrater reliability was higher for CEUS than for B-mode ultrasound (κ=0.941 vs. κ =0.717). Conclusions:Based on an animal model, B-mode ultrasound and CEUS both exhibited good diagnostic efficacy and interrater reliability in evaluating parietal pleural adhesion/invasion of subpleural lung cancer although CEUS outperformed B-mode ultrasound for both measures.